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Imagen de apoyo de  Development and validation of a machine learning-based decision support tool for residency applicant screening and review

Development and validation of a machine learning-based decision support tool for residency applicant screening and review

Por: Jesse; Reinstein Peckel Burk-Rafel | Fecha: 2021

Abstract: Residency programs face overwhelming numbers of residency applications, limiting holistic review. Artificial intelligence techniques have been proposed to address this challenge but have not been created. Here, a multidisciplinary team sought to develop and validate a machine learning (ML)-based decision support tool (DST) for residency applicant screening and review. Results The ML model areas under the receiver operating characteristic and precision recall curves were 0.95 and 0.76, respectively; these changed to 0.94 and 0.72, respectively, with removal of USMLE scores. Applicants’ medical school information was an important driver of predictions—which had face validity based on the local selection process—but numerous predictors contributed. Program directors used the DST in the 2021 application cycle to select 20 applicants for interview that had been initially screened out during human review. Conclusions The authors developed and validated an ML algorithm for predicting residency interview offers from numerous application elements with high performance—even when USMLE scores were removed. Model deployment in a DST highlighted its potential for screening candidates and helped quantify and mitigate biases existing in the selection process. Further work will incorporate unstructured textual data through natural language processing methods.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Development and validation of a machine learning-based decision support tool for residency applicant screening and review

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Imagen de apoyo de  CO2 Capture in a Thermal Power Plant Using Sugarcane Residual Biomass

CO2 Capture in a Thermal Power Plant Using Sugarcane Residual Biomass

Por: Sara Alexandra; Walter Restrepo Valencia | Fecha: 2023

Abstract: The decarbonization of energy matrices is crucial to limit global warming below 2°C this century. An alternative capable of enabling zero or even negative CO2 emissions is bioenergy with carbon capture and storage (BECCS). In this sense, the Brazilian sugar–energy sector draws attention, as it would be possible to combine the production of fuel and electricity from renewable biomass. This paper is the final part of a study that aimed to research carbon capture and storage (CCS) in energy systems based on sugarcane. The case studied is CCS in thermal power plants considering two different technologies: the steam cycle based on the condensing–extraction steam turbine (CEST) and the combined cycle integrated to biomass gasification (BIG-CC). The results for the thermal power plant indicate that the CO2 capture costs may be lower than those in cogeneration systems, which were previously studied. The main reasons are the potential scale effects and the minimization of energy penalties associated with integrating the CCS system into the mills. In the best cases, capture costs can be reduced to EUR 54–65 per ton of CO2 for the CEST technology and EUR 57–68 per ton of CO2 for the BIG-CC technology.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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CO2 Capture in a Thermal Power Plant Using Sugarcane Residual Biomass

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Imagen de apoyo de  Building the future: empowering children to reimagine our cities

Building the future: empowering children to reimagine our cities

Por: Johan Andrés; Chebina Rey Sánchez | Fecha: 2023

Architecture and Urban planning have traditionally been viewed through an adult-centric lens, focusing on adult-scale and experience. However, this approach ignores the valuable insights and perspectives that children can bring to the transformation of our cities. Assemble story began from the desire to make children active participants of society´s transformation and its platform is an instrument to realize it. This is a sample of the process and results in 10 workshops (fall 2022), the collective carried out in Berlin with children between 9-14 years old.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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  • Arte

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Building the future: empowering children to reimagine our cities

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Imagen de apoyo de  Digital mapping of the soil available water capacity: insights for the resilience of agricultural systems to climate change

Digital mapping of the soil available water capacity: insights for the resilience of agricultural systems to climate change

Por: Andrés Mauricio; De Jong van Lier Rico Gómez | Fecha: 2023

Abstract: Soil available water capacity (AWC) is a key function for human survival and well-being. However, its direct measurement is laborious and spatial interpretation is complex. Digital soil mapping (DSM) techniques emerge as an alternative to spatial modeling of soil properties. DSM techniques commonly apply machine learning (ML) models, with a high level of complexity. In this context, we aimed to perform a digital mapping of soil AWC and interpret the results of the Random Forest (RF) algorithm and, in a case study, to show that digital AWC maps can support agricultural planning in response to the local effects of climate change. To do so, we divided this research into two approaches: In the first approach, we showed a DSM using 1857 sample points in a southeastern region of Brazil with laboratory-determined soil attributes, together with a pedotransfer function (PTF), remote sensing and DSM techniques. In the second approach, the constructed AWC digital soil map and weather station data were used to calculate climatological soil water balances for the periods between 1917–1946 and 1991–2020. The result showed the selection of covariates using Shapley values as a criterion contributed to the parsimony of the model, obtaining goodness-of-fit metrics of R2 0.72, RMSE 16.72 mm m?1, CCC 0.83, and Bias of 0.53 over the validation set. The highest contributing covariates for soil AWC prediction were the Landsat multitemporal images with bare soil pixels, mean diurnal, and annual temperature range. Under the current climate conditions, soil available water content (AW) increased during the dry period (April to August). May had the highest increase in AW (?17 mm m?1) and decrease in September (?14 mm m?1). The used methodology provides support for AWC modeling at 30 m resolution, as well as insight into the adaptation of crop growth periods to the effects of climate change.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Digital mapping of the soil available water capacity: insights for the resilience of agricultural systems to climate change

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Imagen de apoyo de  Active Confinement of RC Columns with External Post-tensioned Clamps = Confinamiento Activo de Columnas de Concreto Reforzado con Abrazaderas Presforzadas

Active Confinement of RC Columns with External Post-tensioned Clamps = Confinamiento Activo de Columnas de Concreto Reforzado con Abrazaderas Presforzadas

Por: Julián David; Skillen Rincón Gil | Fecha: 2023

Abstract: There are too many reinforced concrete (RC) columns built before mid-1970s without sufficient transverse reinforcement. By now, we understand quite well the importance of transverse reinforcement in allowing a column to maintain its integrity under large displacement reversals in the nonlinear range of response. Poorly confined RC columns undergo a fast decay in resistance due to formation of criss-crossing inclined cracks, which can cause an abrupt failure or more gradual disintegration and trigger collapse of the structure. Those columns need to be strengthened to increase their drift capacity. Although there are several alternatives to retrofit RC columns, they often require specialized workmanship and equipment, and involved installation procedures. An easy-todesign and easyto-implement retrofit technique is examined here. It consists of external posttensioned clamps fastened around the column. Results of tests on full-scale RC columns furnished with the proposed clamps suggest the clamps can be effective in increasing column shear strength and drift capacity. Resumen: Muchas columnas de concreto reforzado construidas antes de mediados de la década de 1970 tienen insuficiente refuerzo transversal. Hace solo un par de décadas que se entendió la importancia del refuerzo transversal para permitir que una columna mantenga su integridad bajo grandes desplazamientos en el rango de respuesta no lineal. Las columnas de concreto reforzado mal confinadas sufren una rápida disminución de la resistencia debido a la formación de grietas, que pueden causar una falla abrupta o una desintegración más gradual y desencadenar el colapso de la estructura. Es necesario reforzar dichas columnas para aumentar su capacidad de deriva. Aunque existen varias alternativas para reforzar columnas de concreto reforzado, a menudo requieren mano de obra y equipo especializados, además de procedimientos de instalación complicados. Aquí se examina una técnica de reforzamiento fácil de diseñar e implementar. La técnica consta de abrazaderas presforzadas externas fijadas alrededor de la columna. Los resultados de laboratorio de las columnas de concreto reforzado a gran escala equipadas con las abrazaderas propuestas sugieren que las abrazaderas pueden ser efectivas para aumentar la resistencia al corte y la capacidad de deriva de la columna.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Active Confinement of RC Columns with External Post-tensioned Clamps = Confinamiento Activo de Columnas de Concreto Reforzado con Abrazaderas Presforzadas

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Imagen de apoyo de  Benchmarking Transfer Entropy Methods for the Study of Linear and Nonlinear Cardio-Respiratory Interactions = Evaluación comparativa de métodos de entropía de transferencia para el estudio de interacciones cardiorrespiratorias lineales y no lineales

Benchmarking Transfer Entropy Methods for the Study of Linear and Nonlinear Cardio-Respiratory Interactions = Evaluación comparativa de métodos de entropía de transferencia para el estudio de interacciones cardiorrespiratorias lineales y no lineales

Por: Carmen Andrea; Moeyersons Rozo Méndez | Fecha: 2021

Abstract: Transfer entropy (TE) has been used to identify and quantify interactions between physiological systems. Different methods exist to estimate TE, but there is no consensus about which one performs best in specific applications. In this study, five methods (linear, k-nearest neighbors, fixed-binning with ranking, kernel density estimation and adaptive partitioning) were compared. The comparison was made on three simulation models (linear, nonlinear and linear + nonlinear dynamics). From the simulations, it was found that the best method to quantify the different interactions was adaptive partitioning. This method was then applied on data from a polysomnography study, specifically on the ECG and the respiratory signals (nasal airflow and respiratory effort around the thorax). The hypothesis that the linear and nonlinear components of cardio-respiratory interactions during light and deep sleep change with the sleep stage, was tested. Significant differences, after performing surrogate analysis, indicate an increased TE during deep sleep. However, these differences were found to be dependent on the type of respiratory signal and sampling frequency. These results highlight the importance of selecting the appropriate signals, estimation method and surrogate analysis for the study of linear and nonlinear cardio-respiratory interactions. Resumen: La entropía de transferencia (TE) se ha utilizado para identificar y cuantificar las interacciones entre sistemas fisiológicos. Existen diferentes métodos para estimar la TE, pero no hay consenso sobre cuál funciona mejor en aplicaciones específicas. En este estudio, se compararon cinco métodos (lineal, k-nearest neighbors, fixed binning with ranking, kernel density estimation, and adaptive partitioning). La comparación se realizó en tres modelos de simulación (lineal, no lineal y dinámicas lineales + no lineales). A partir de las simulaciones, se encontró que el mejor método para cuantificar las diferentes interacciones fue el adaptive partitioning. Este método se aplicó luego a datos de un estudio de polisomnografía, específicamente a las señales de ECG y respiratorias (flujo nasal y esfuerzo respiratorio alrededor del tórax). Se probó la hipótesis de que los componentes lineales y no lineales de las interacciones cardiorespiratorias durante el sueño ligero y profundo cambian con la etapa del sueño. Diferencias significativas, después de realizar un análisis de subrogados, indican un aumento en la TE durante el sueño profundo. Sin embargo, se encontró que estas diferencias dependían del tipo de señal respiratoria y la frecuencia de muestreo. Estos resultados resaltan la importancia de seleccionar las señales apropiadas, el método de estimación y el análisis de subrogados adecuados para el estudio de las interacciones cardiorespiratorias lineales y no lineales.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Benchmarking Transfer Entropy Methods for the Study of Linear and Nonlinear Cardio-Respiratory Interactions = Evaluación comparativa de métodos de entropía de transferencia para el estudio de interacciones cardiorrespiratorias lineales y no lineales

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Imagen de apoyo de  Data Augmentation and Transfer Learning for Data Quality Assessment in Respiratory Monitoring = Aumento de datos y transferencia de aprendizaje para la evaluación de la calidad de datos en monitoreo respiratorio

Data Augmentation and Transfer Learning for Data Quality Assessment in Respiratory Monitoring = Aumento de datos y transferencia de aprendizaje para la evaluación de la calidad de datos en monitoreo respiratorio

Por: Carmen Andrea; Moeyersons Rozo Mendez | Fecha: 2022

Abstract: Changes in respiratory rate have been found to be one of the early signs of health deterioration in patients. In environments where diagnostic tools and medical attention are scarce, the monitoring of the respiratory signal becomes crucial to timely detect life-threatening conditions. This signal can be measured using wearable technology; however, the use of such technology is often hampered by the low quality of the recordings. Therefore, to apply these data in diagnosis, it is important to determine which parts of the signal are of sufficient quality. This study aims to evaluate the performance of a signal quality assessment framework, where two machine learning algorithms (support vector machine-SVM, and convolutional neural network-CNN) were used. The models were pretrained using data of patients suffering from chronic obstructive pulmonary disease. The generalization capability of the models was evaluated by testing them on data from a different patient population, presenting normal and pathological breathing. The new patients underwent bariatric surgery and performed a controlled breathing protocol, displaying six different breathing patterns. Data augmentation (DA) and transfer learning (TL) were used to increase the size of the training set and to optimize the models for the new dataset. The effect of the different breathing patterns on the performance of the classifiers was also studied. The SVM did not improve when using DA, however, when using TL, the performance improved significantly (p<0.05) compared to DA. The opposite effect was observed for CNN, where the biggest improvement was obtained using DA. The models presented a low performance for shallow, slow and fast breathing patterns. These results suggest that it is possible to classify respiratory signals obtained with wearable technologies using pretrained machine learning models. Resumen: Se ha encontrado que cambios en la frecuencia respiratoria son uno de los primeros signos de deterioro de la salud en pacientes. En entornos donde las herramientas de diagnóstico y la atención médica son escasas, el monitoreo de la señal respiratoria se vuelve crucial para detectar de manera oportuna condiciones que amenazan la vida. Esta señal se puede medir mediante tecnología portátil; sin embargo, el uso de dicha tecnología a menudo se ve obstaculizado por la baja calidad de las señales. Por lo tanto, para aplicar estos datos para diagnóstico, es importante determinar qué partes de la señal tienen una calidad suficientemente buena. Este estudio tiene como objetivo evaluar el rendimiento de un marco de evaluación de calidad de señal, donde se utilizaron dos algoritmos de aprendizaje automático (máquina de soporte vectorial-SVM y red neuronal convolucional-CNN). Los modelos fueron preentrenados utilizando datos de pacientes que padecen enfermedad pulmonar obstructiva crónica. La capacidad de generalización de los modelos se evaluó probándolos en datos de una población de pacientes diferente, que presentaban respiración normal y patológica. Los nuevos pacientes se sometieron a cirugía bariátrica y realizaron un protocolo de respiración controlada, mostrando seis patrones de respiración diferentes. Se utilizó aumento de datos (AD) y transferencia de aprendizaje (TL) para aumentar el tamaño del conjunto de entrenamiento y optimizar los modelos para el nuevo conjunto de datos. Se estudió también el efecto de los diferentes patrones de respiración en el rendimiento de los clasificadores. La SVM no mejoró al usar AD, sin embargo, al usar TL, el rendimiento mejoró significativamente (p<0.05) en comparación con AD. Se observó el efecto contrario en CNN, donde la mayor mejora se obtuvo con AD. Los modelos presentaron un bajo rendimiento para patrones de respiración superficiales, lentos y rápidos. Estos resultados sugieren que es posible clasificar las señales respiratorias obtenidas con tecnologías portátiles mediante modelos preentrenados de aprendizaje automático.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Data Augmentation and Transfer Learning for Data Quality Assessment in Respiratory Monitoring = Aumento de datos y transferencia de aprendizaje para la evaluación de la calidad de datos en monitoreo respiratorio

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Imagen de apoyo de  Do former Mine Sites still pose an Environmental Impact? A Case Study in Southern Scotland

Do former Mine Sites still pose an Environmental Impact? A Case Study in Southern Scotland

Por: Mónica; Mbadigha Rincón Ojeda | Fecha: 2019

Abstract: Abandoned mines are generally associated with the release of heavy metals into the environment. Through mine water, numerous streams and rivers in Scotland are currently severely polluted with potentially toxic metals. To determine the magnitude of the contamination by Pb, Zn, Cu, and Cd in the Glengonnar catchment, along with their spatial variation and potential risk to human health and surface water, sediment and water samples were collected at different locations along a section of the catchment. Heavy metals concentrations were determined by MP – AES and AAS, their spatial variation was observed through SEM – EDS, and the risk assessment was conducted through RISC5 software and Remedial Targets Methodology. Concentrations of metals were higher in sediments (up to 70,668.41 mg/kg Pb, 3,802.48 mg/kg Zn, and 1,078.60 mg/kg Cu) than in water (up to 2,385.16 ?g/L Pb, and 334.52 ?g/L Zn), as a result of the speciation and the adsorption-distribution coefficient of metals, together with the pH of the water. Metals, as free ions and in particulate form, were found to be present at Pb processing and Pb mining areas, respectively. Risk assessment revealed that Pb is the metal of greatest concern and concentrations are prone to harm human health. No detrimental effects to human health were related with concentrations of Zn and Cu in water or sediments. Concentrations of Pb, Zn and Cu in sediments represent a considerable risk to the aquatic environment of the surface water. Consequently, historical legacy of the mining operations at Leadhills means that risk to human health and surface water is present and is likely to continue; reason why adequate mitigation techniques are required in order to decrease pollution and dispersion of heavy metals.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Do former Mine Sites still pose an Environmental Impact? A Case Study in Southern Scotland

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Imagen de apoyo de  The evolutionary mechanism of non-carbapenemase carbapenem-resistant phenotypes in Klebsiella spp

The evolutionary mechanism of non-carbapenemase carbapenem-resistant phenotypes in Klebsiella spp

Por: Natalia Carolina; Wilksch Rosas Bastidas | Fecha: 2023

Abstract: Antibiotic resistance is driven by selection, but the degree to which a bacterial strain’s evolutionary history shapes the mechanism and strength of resistance remains an open question. Here, we reconstruct the genetic and evolutionary mechanisms of carbapenem resistance in a clinical isolate of Klebsiella quasipneumoniae. A combination of short- and long-read sequencing, machine learning, and genetic and enzymatic analyses established that this carbapenem-resistant strain carries no carbapenemase-encoding genes. Genetic reconstruction of the resistance phenotype confirmed that two distinct genetic loci are necessary in order for the strain to acquire carbapenem resistance. Experimental evolution of the carbapenem-resistant strains in growth conditions without the antibiotic revealed that both loci confer a significant cost and are readily lost by de novo mutations resulting in the rapid evolution of a carbapenem-sensitive phenotype. To explain how carbapenem resistance evolves via multiple, low-fitness single-locus intermediates, we hypothesised that one of these loci had previously conferred adaptation to another antibiotic. Fitness assays in a range of drug concentrations show how selection in the antibiotic ceftazidime can select for one gene (blaDHA-1) potentiating the evolution of carbapenem resistance by a single mutation in a second gene (ompK36). These results show how a patient’s treatment history might shape the evolution of antibiotic resistance and could explain the genetic basis of carbapenem-resistance found in many enteric-pathogens.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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  • Medicina

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The evolutionary mechanism of non-carbapenemase carbapenem-resistant phenotypes in Klebsiella spp

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Imagen de apoyo de  Controlled Breathing Effect on Respiration Quality Assessment Using Machine Learning Approaches = Efecto de la Respiración Controlada en la Evaluación de la Calidad de la Respiración Utilizando Enfoques de Aprendizaje Automático

Controlled Breathing Effect on Respiration Quality Assessment Using Machine Learning Approaches = Efecto de la Respiración Controlada en la Evaluación de la Calidad de la Respiración Utilizando Enfoques de Aprendizaje Automático

Por: Carmen Andrea; Buil Rozo Mendez | Fecha: 2021

Abstract: Thoracic bio-impedance (BioZ) measurements have been proposed as an alternative for respiratory monitoring. Given the ambulatory nature of this modality, it is more prone to noise sources. In this study, two pre-trained machine learning models were used to classify BioZ signals into clean and noisy classes. The models were trained on data from patients suffering from chronic obstructive pulmonary disease, and their performance was evaluated on data from patients undergoing bariatric surgery. Additionally, transfer learning (TL) was used to optimize the models for the new patient cohort. Lastly, the effect of different breathing patterns on the performance of the machine learning models was studied. Results showed that the models performed accurately when applying them to another patient population and their performance was improved by TL. However, different imposed respiratory frequencies were found to affect the performance of the models. Abstract: Las mediciones de bioimpedancia torácica (BioZ) se han propuesto como una alternativa para el monitoreo respiratorio. Dada la naturaleza ambulatoria de esta modalidad, es más propensa a fuentes de ruido. En este estudio, se utilizaron dos modelos de aprendizaje automático preentrenados para clasificar las señales de BioZ en clases limpias y ruidosas. Los modelos se entrenaron con datos de pacientes que padecen enfermedad pulmonar obstructiva crónica, y su rendimiento se evaluó en datos de pacientes sometidos a cirugía bariátrica. Además, se utilizó la transferencia de aprendizaje (TL) para optimizar los modelos para la nueva cohorte de pacientes. Por último, se estudió el efecto de diferentes patrones de respiración en el rendimiento de los modelos de aprendizaje automático. Los resultados mostraron que los modelos funcionaron con precisión al aplicarlos a otra población de pacientes y su rendimiento mejoró mediante TL. Sin embargo, se encontró que diferentes frecuencias respiratorias impuestas afectaban el rendimiento de los modelos.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
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Controlled Breathing Effect on Respiration Quality Assessment Using Machine Learning Approaches = Efecto de la Respiración Controlada en la Evaluación de la Calidad de la Respiración Utilizando Enfoques de Aprendizaje Automático

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